Subacute and subchronic intoxication by hydrazine, mono methyl hydrazine, 1,1 dimethyl hydrazine, and benzyl hydrazine is under study. Minimum effective parenteral dose rates for a three week work day-work week treatment schedule will be established for inhibition of in vivo oxidation of methyl amine-C14, putrescine-C14 amino butyric acid-C14 and ornithine-C14. Each substrate is metabolised by a system known to be sensitive to some or all of the listed hydrazines. A toxic steady state will be sought in which the rate of recovery balances loss of function due to intoxication. Duration of recovery will be measured, Intestinal diamine oxidase and brain and liver mono amine oxidase activity of selected intoxicated animals will be evaluated in vitro. Effects of the hydrazines on ornithine decarboxylase of regenerating rat liver and the high diamine oxidase of rat placenta and pregnancy plasma will also be examined.